Tell it like it is

To win the Cannes Film Festival's prestigious Palme d'Or twice puts you in an elite group - Alf Sjoberg, Francis Ford Coppola, Emir Kusturica, Bille August and Shohei Imamura, to be precise. The most recent additions to this select band are Jean-Pierre and Luc Dardenne, the Belgian siblings who gained entrance when they won the Palme d'Or in 2005 for The Child, their second film to scoop the award after 1999's Rosetta.

Inevitably, the question turns to how they would feel if they won an unprecedented third. 'We don't listen to the song of the mermaids who would like to take us down to the bottom of the sea because we don't know how to swim and we would drown,' says Luc. It's about as oblique an answer as Eric Cantona talking about seagulls and trawlers. Still, it suits the Dardenne brothers' latest drama, the mysterious The Silence of Lorna.

As it turns out, they did not win the top prize when the film played at Cannes last year. But they did not go home empty-handed. The film won the award for best screenplay, confirming that in just 10 years the Dardennes have become regarded as two of Europe's most important filmmakers. Not that they act like it: the silver-haired Jean-Pierre, 58, and Luc, 55, are quiet and unassuming individuals. Such is their gentle manner that it's not hard to understand why their films are laced with humanity.

Like the Flemish equivalent of Ken Loach, the Dardennes are hooked on observing the disenfranchised, those who belong to society's so-called underclass. The 1996 film The Promise, their third feature but the first that attracted international attention, dealt with the exploitation of illegal immigrants on a building site. Rosetta was about a young girl living with her alcoholic mother in a caravan park; The Child followed a petty thief and his girlfriend struggling to make ends meet after she gives birth to their baby.

So what makes them return to such characters? 'I think mainly it's because we like them and we like their stories,' says Jean-Pierre. 'That's first and foremost. We like to film them and maybe this is partly because we see them less. Also, I feel maybe by approaching the margins we can better see what's in the centre. We feel close to these characters - we like them. Even if sometimes they're very bad, we still like them.

'When we start out to make a film, we don't really think about what milieu we're going to set it in, what social class. We think more about individuals and situations they could be in.'

Set in Belgium's post-industrial town of Liege, The Silence of Lorna is no exception to their oeuvre, once again using the subject of immigration as a springboard towards wider issues. Lorna (Arta Dobroshi) is an Albanian twentysomething who has married heroin addict Claudy (Dardenne regular Jeremie Renier) to gain a Belgian passport. While Lorna dreams of opening a restaurant, the local gangsters who arranged her citizenship have other plans for her. Primarily, this involves wedding her to a Russian, something that will have fatal consequences.

The story began fermenting in the brothers' minds seven years ago when they met a woman who worked with homeless people. 'She told us a story about her brother who was a junkie, who was approached by the Albanian mafia in Belgium about an arranged marriage,' says Luc. 'He'd been offered the chance to enter into a contract like this, where he would make a certain amount of money upon the marriage and then double that on the divorce.'

Being the streetwise one of the family, the sister had heard of such schemes - which usually ended in the death of the junkie. She advised her brother against the ruse and he listened. But as far as the Dardenne brothers were concerned, the story had only just begun. 'We were thinking about what it would be like for a woman to find herself in this dilemma,' says Jean-Pierre, 'between wanting to pursue her dream of a better life and the fact that this was going to entail the death of somebody.'

Invariably, the film raises questions about the thorny issue of immigration. The brothers both belong to CIRE (Co-ordination and Initiatives for Refugees and Foreigners), a movement that fights for legislation to protect those who leave their homeland behind and arrive in European countries. 'By helping the immigrants, by having ways to bring families together, by making things clearer, we can also help fight the underground that really develops, like the Albanian underground, that then exploits people who are coming and needing papers,' says Luc.

'We need to have a system of solidarity to help immigrants in our countries and help them have a clearer legal status that doesn't then make them fall prey to these situations,' Jean-Pierre says, suddenly very animated. 'The problem these days is the fear factor. Often politicians fall into it to get votes and play on the fears of people who are afraid of too many people coming in. That's too easy. We need to fight against that.'

Although the Dardennes hail from a middle-class background - Jean-Pierre trained as an actor, Luc studied philosophy - the affinity they show for the less fortunate is matched by their refusal to patronise their subjects. Co-founding Derives, their production house since 1975, the pair began documenting on video working-class lives on council estates.

Subsequently producing many documentaries, they strove to remain observers - and not champions - of those they portray. Neither do their films seek to unearth 'culprits and victims', they say, when asked whether their work is politically motivated. 'For us, the moral question is more interesting than the political question. How social fate can lead a character to murder, for example.'

Ever since their first feature film, Falsch (1987), a post-second world war drama that dealt with a Jewish family reunited in the afterlife, their work has also been invested with considerable spirituality. The latter half of The Silence of Lorna is no exception, emerging like a religious parable. 'We're not personally religious but religion is a big part of the human story,' says Luc. 'Whoever wrote the Ten Commandments clearly understood something fundamental about human beings and it would be wrong to ignore that just because you don't believe in God.'

Like other fraternal filmmakers - the Coens and the Quays - the Dardennes share virtually all the tasks in the filmmaking process. 'We do everything together,' says Jean-Pierre, who points out that on set while one will sit by the monitor, the other will work with the actors, before they switch. As for pre-production, 'Luc writes the script but we construct the story together, and imagine the different scenes and all that stuff. Then at the end, we are together with the editor, and the sound mixer - and the journalists.'

Indeed, just as it's unlikely that they'll ever change their working methods, it's hard to believe they will ever switch their attention from observing the poor and the needy in their own backyard. Certainly, there's no reason for them to change. While Rosetta was once labelled 'the future of cinema' by Canadian director David Cronenberg, Cannes jury president the year they won their first Palme d'Or, maybe the same can now be said of the brothers themselves.

The Silence of Lorna opens on May 28